1. Field of the Invention
The present invention relates to a method and apparatus for controlling operation of a throttle valve, based on an accelerator pedal signal, in a vehicle having an automatic transmission system including an electric control circuit, such as a microcomputer.
The present invention can automatically control the operation of a throttle valve in accordance with predetermined control maps stored in a read-only memory (ROM) in the microcomputer, thereby allowing easy driving under all driving conditions.
2. Description of the Prior Art
As is well known, it is troublesome for a driver, especially an unskilled driver, to operate a clutch pedal, accelerator pedal, and change lever all at once. It is troublesome and tiring even for a skilled driver to operate the same over long distances or start-and-stop traffic.
Recently, increasing use has been made of automatic transmission systems using so-called torque converters. These eliminate the awkward clutch operation and automate the gear change operation. But using a torque converter, the driver need only operate the accelerator pedal and brake pedal. Therefore, even an unskilled driver can easily drive under all driving conditions.
While an automobile equipped with a torque-converter type automatic transmission offers many advantages in terms of driveability, it requires more careful maintenance and costs more due to the many complex mechanisms incorporated therein. For example, due to the need for precise control for obtaining smooth driving equal to that offered by a manual transmission, it requires a large oil pressure circuit for controlling the transmission mechanism.
Also, as opposed to a manual transmission car where the engine power is transmitted to the drive wheels via a mechanical coupling, an automobile having an automatic transmission uses fluid coupling for transmission of engine power. As a result, it suffers from inferior transmission efficiency of the engine power and thus poorer fuel consumption efficiency. Moreover, slip loss occurs during transmission of power, making it difficult to obtain the desired acceleration along with the operation of the accelerator pedal.
Moreover, when braking, the driver must frequently operate the brake pedal due to the somewhat poor effect of engine braking.